The source and drain regions of n-type metal-oxide-semiconductor (NMOS) field-effect transistors (FETs) need to have n-type impurities. The commonly used n-type impurities include phosphorous and arsenic. Conventionally, when arsenic is doped, it is implanted into the source and drain regions, for example, by using AsH3 as the dopant-containing process gas.
The implanted arsenic, however, is not activated. To cure the implanted arsenic, and also to cure the crystalline structure in the source and drain regions, thermal processes are necessary. The thermal processes cause the undesirable dopant diffusion, which leads to the loss of junction abruptness. Furthermore, the thermal processes also cause thermal budget issues in the manufacturing of the integrated circuits.